Method of using dermatomal somatosensory evoked potentials in real-time for surgical and clinical management

Abstract

Methods, computer systems and apparatus are provided for neurophysiological assessment, specifically evaluation of mixed and dermatomal nerve conduction latencies and amplitudes, as well as electrophysiological evaluation of spontaneous electromyogram. Software guides the user through protocol selection, electrode placement, baseline determinations, comparisons to normal data, post-manipulation comparisons, displayed warning of pathological changes, archiving of data and report generation.

1 . A method of comparing and assessing evoked potentials elicited by a stimulating electrode at a stimulation site on a mammalian subject during a procedure and stored in a data storage system, the method comprising: 
 a) eliciting an evoked potential response from a first stimulation site on the subject, receiving and amplifying a stimulation signal, and recording the waveform signal;    b) automatically digitally converting the waveform signal and assigning numeric values for the absolute amplitude and absolute latency of the waveform;    c) replicating the steps a) and b) to obtain a series of replicated digitally assigned waveform data for the given stimulation site; and    d) mathematically conditioning the replicated digitally assigned waveform data, obtaining a validated mean value for the waveform data, then comparing the validated mean value with protocol-specific and subject-specific normal data, wherein the comparison is assessed and the deviations of the waveform data from normal noted.    
     
     
         2 . The method of  claim 1 , wherein the steps a) to d) are performed serially with respect to two or more different stimulation sites on the subject.  
     
     
         3 . The method of  claim 1 , wherein the evoked potential responses are recorded exclusively at a subcortical recording site on the subject.  
     
     
         4 . The method of  claim 1 , wherein the obtained data are correlated with electromyogram (EMG) data obtained from the same subject.  
     
     
         5 . The method of  claim 1 , further consisting of comparing and evaluating the waveform data in real-time as a function of time, the method further comprising: 
 e) performing a series of further trials in the manner of steps a) to d) and serially comparing and evaluating in real-time the changes in the waveform data; and    f) saving the comparisons and changes as a function of time.    
     
     
         6 . The method of  claim 5 , wherein steps a)-f) are carried out with respect to a second or a plurality of different stimulation sites on the subject.  
     
     
         7 . The method of  claim 5 , wherein the evoked potential responses are recorded exclusively at a subcortical recording site on the subject.  
     
     
         8 . The method of  claim 5 , wherein the obtained data are correlated with electromyogram (EMG) data obtained from the same subject.  
     
     
         9 . A computer readable medium having encoded instructions for executing the methods of claims  1  and  5 .  
     
     
         10 . A computer program storage medium readable by a computing system and encoding a computer program for executing a computer process, the program comprising instructions for executing the methods of claims  1  and  5 .  
     
     
         11 . A computer data signal embodied in a carrier wave by a computing system and encoding a computer program for executing a computer process, the program comprising instructions for executing the methods of claims  1  and  5 .  
     
     
         12 . An apparatus for comparing and assessing evoked potentials elicited by a stimulating electrode at a stimulation site on a mammalian subject during a procedure, the apparatus comprising: 
 a) hardware means for eliciting an evoked potential response from a first stimulation site on the subject, receiving and amplifying a stimulation signal, and recording the waveform signal;    b) hardware means for automatically digitally converting the waveform signal and software means for assigning numeric values for the absolute amplitude and absolute latency of the waveform;    c) hardware and software means for replicating the steps a) and b) to obtain a series of replicated digitally assigned waveform data for the given stimulation site; and    d) software means for mathematically conditioning the replicated digitally assigned waveform data, obtaining a validated mean value for the waveform data, then comparing the validated mean value with protocol-specific and subject-specific normal data, wherein the comparison is assessed and the deviations of the waveform data from normal noted.    
     
     
         13 . The apparatus of  claim 12 , wherein steps a) and b) are serially performed with respect to two or more different stimulation sites on the subject.  
     
     
         14 . The apparatus of  claim 12 , further comprising a hardware means for recording the evoked potential responses at a subcortical recording site on the subject.  
     
     
         15 . The apparatus of  claim 12 , further comprising software means for correlating the obtained data with electromyogram (EMG) data obtained from the same subject.  
     
     
         16 . The apparatus of  claim 12 , further comprising software means for: 
 e) performing a series of further trials in the manner of steps a) to d) and serially comparing and evaluating in real-time the changes in the waveform data; and    f) saving the comparisons and changes as a function of time.    
     
     
         17 . The apparatus of  claim 16 , the steps a)-f) are carried out with respect to a second or a plurality of different stimulation sites on the subject.  
     
     
         18 . The apparatus of  claim 16 , further comprising a hardware means for recording the evoked potential responses at a subcortical recording site on the subject.  
     
     
         19 . The apparatus of  claim 16 , further comprising software means for correlating the waveform data with electromyogram (EMG) data obtained from the same subject.  
     
     
         20 . The apparatus of either of claims  16  and  19 , further comprising a patient connection means connected between the subject and the computer and comprising a plurality of receptor sites for inserting multiple stimulating and recording electrodes, wherein the receptor sites for inserting stimulating electrodes correlate with placement of stimulating electrodes on the subject; and 
 wherein the receptor sites for inserting recording electrodes correlate with placement of recording electrodes on the subject.    
     
     
         21 . The apparatus of  claim 20 , further comprising a stimulus switchbox means connected between the patient connection means and an A/D converter means, wherein the stimulus switchbox means provides for instrumental control of a plurality of recording and stimulating electrodes.  
     
     
         22 . The apparatus of  claim 20 , further comprising a software means for generating a deviation from normal warning signal via a visual, audible or electronic means.  
     
     
         23 . The apparatus of  claim 20 , further comprising a software means for providing and displaying an icon on a computer screen responsive to a command by a computer user, wherein the icon appears on the screen and prompts a user to select an option consisting of take a patient history, select a recording protocol, confirm proper electrode placement, input parameters, record a sequence, analyze data, archive data, or generate a report.